1 /* 2 * Common signal handling code for both 32 and 64 bits 3 * 4 * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration 5 * Extracted from signal_32.c and signal_64.c 6 * 7 * This file is subject to the terms and conditions of the GNU General 8 * Public License. See the file README.legal in the main directory of 9 * this archive for more details. 10 */ 11 12 #include <linux/tracehook.h> 13 #include <linux/signal.h> 14 #include <linux/uprobes.h> 15 #include <linux/key.h> 16 #include <asm/hw_breakpoint.h> 17 #include <asm/uaccess.h> 18 #include <asm/unistd.h> 19 #include <asm/debug.h> 20 21 #include "signal.h" 22 23 /* Log an error when sending an unhandled signal to a process. Controlled 24 * through debug.exception-trace sysctl. 25 */ 26 27 int show_unhandled_signals = 0; 28 29 /* 30 * Allocate space for the signal frame 31 */ 32 void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, 33 size_t frame_size, int is_32) 34 { 35 unsigned long oldsp, newsp; 36 37 /* Default to using normal stack */ 38 oldsp = get_clean_sp(regs, is_32); 39 40 /* Check for alt stack */ 41 if ((ka->sa.sa_flags & SA_ONSTACK) && 42 current->sas_ss_size && !on_sig_stack(oldsp)) 43 oldsp = (current->sas_ss_sp + current->sas_ss_size); 44 45 /* Get aligned frame */ 46 newsp = (oldsp - frame_size) & ~0xFUL; 47 48 /* Check access */ 49 if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp)) 50 return NULL; 51 52 return (void __user *)newsp; 53 } 54 55 static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka, 56 int has_handler) 57 { 58 unsigned long ret = regs->gpr[3]; 59 int restart = 1; 60 61 /* syscall ? */ 62 if (TRAP(regs) != 0x0C00) 63 return; 64 65 /* error signalled ? */ 66 if (!(regs->ccr & 0x10000000)) 67 return; 68 69 switch (ret) { 70 case ERESTART_RESTARTBLOCK: 71 case ERESTARTNOHAND: 72 /* ERESTARTNOHAND means that the syscall should only be 73 * restarted if there was no handler for the signal, and since 74 * we only get here if there is a handler, we dont restart. 75 */ 76 restart = !has_handler; 77 break; 78 case ERESTARTSYS: 79 /* ERESTARTSYS means to restart the syscall if there is no 80 * handler or the handler was registered with SA_RESTART 81 */ 82 restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0; 83 break; 84 case ERESTARTNOINTR: 85 /* ERESTARTNOINTR means that the syscall should be 86 * called again after the signal handler returns. 87 */ 88 break; 89 default: 90 return; 91 } 92 if (restart) { 93 if (ret == ERESTART_RESTARTBLOCK) 94 regs->gpr[0] = __NR_restart_syscall; 95 else 96 regs->gpr[3] = regs->orig_gpr3; 97 regs->nip -= 4; 98 regs->result = 0; 99 } else { 100 regs->result = -EINTR; 101 regs->gpr[3] = EINTR; 102 regs->ccr |= 0x10000000; 103 } 104 } 105 106 static int do_signal(struct pt_regs *regs) 107 { 108 sigset_t *oldset = sigmask_to_save(); 109 siginfo_t info; 110 int signr; 111 struct k_sigaction ka; 112 int ret; 113 int is32 = is_32bit_task(); 114 115 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 116 117 /* Is there any syscall restart business here ? */ 118 check_syscall_restart(regs, &ka, signr > 0); 119 120 if (signr <= 0) { 121 /* No signal to deliver -- put the saved sigmask back */ 122 restore_saved_sigmask(); 123 regs->trap = 0; 124 return 0; /* no signals delivered */ 125 } 126 127 #ifndef CONFIG_PPC_ADV_DEBUG_REGS 128 /* 129 * Reenable the DABR before delivering the signal to 130 * user space. The DABR will have been cleared if it 131 * triggered inside the kernel. 132 */ 133 if (current->thread.dabr) 134 set_dabr(current->thread.dabr, current->thread.dabrx); 135 #endif 136 /* Re-enable the breakpoints for the signal stack */ 137 thread_change_pc(current, regs); 138 139 if (is32) { 140 if (ka.sa.sa_flags & SA_SIGINFO) 141 ret = handle_rt_signal32(signr, &ka, &info, oldset, 142 regs); 143 else 144 ret = handle_signal32(signr, &ka, &info, oldset, 145 regs); 146 } else { 147 ret = handle_rt_signal64(signr, &ka, &info, oldset, regs); 148 } 149 150 regs->trap = 0; 151 if (ret) { 152 signal_delivered(signr, &info, &ka, regs, 153 test_thread_flag(TIF_SINGLESTEP)); 154 } 155 156 return ret; 157 } 158 159 void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags) 160 { 161 if (thread_info_flags & _TIF_UPROBE) 162 uprobe_notify_resume(regs); 163 164 if (thread_info_flags & _TIF_SIGPENDING) 165 do_signal(regs); 166 167 if (thread_info_flags & _TIF_NOTIFY_RESUME) { 168 clear_thread_flag(TIF_NOTIFY_RESUME); 169 tracehook_notify_resume(regs); 170 } 171 } 172 173 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 174 unsigned long r5, unsigned long r6, unsigned long r7, 175 unsigned long r8, struct pt_regs *regs) 176 { 177 return do_sigaltstack(uss, uoss, regs->gpr[1]); 178 } 179